Brain hypoperfusion patients may cause vascular dementia results from their hypoperfusion state except that is a risk factor for stroke. The most common clinical symptom of hypoperfusion syndrome is dizziness.Siwu tang is made of Angelica sinensis (Oliv.) Diels (當歸), Rehmannia glutinosa (Gaertn) Libosch (熟地黃), Paeonia lactiflora Pall (白芍), Ligusticum chuanxiong Hort (川芎), and that was used to treat patients with blood deficiency for several centuries. the purpose of the present study was to investigate the complementary effect of siwu tang on brain hypoperfusion syndrome patients